In recent years, there have been proposed and developed various automotive lane deviation avoidance technologies. An automotive lane deviation avoidance system, capable of executing a lane deviation avoidance control function that corrects the host vehicle's course in the direction of lane deviation avoidance, has been disclosed in Japanese Patent Provisional Publication No. 9-142327 (hereinafter is referred to as “JP9-142327”). In the lane deviation preventing device disclosed in JP9-142327, an electronic control unit (ECU) determines that a steering operation is made with a driver's intention for lane changing or collision avoidance with the frontally-located object when at least one of a steering velocity, a steering torque, and a time rate of change in steering torque becomes greater than or equal to a threshold value. When the ECU determines the presence of the driver's intention for lane changing or collision avoidance, the ECU disables or disengages or regulates operations of actuators used for lane deviation avoidance control, for example, brake actuators, a steering actuator, a throttle actuator, and an alarm actuator so as to avoid an undesirable control interference between lane deviation avoidance control and actions taken manually by the driver or an undesirable control interference between lane deviation avoidance control and vehicle dynamics control that reduces a turning level to achieve a transition from an unstable driving state (a poor driving stability) approximate to the vehicle's limit drivability to a stable driving state (a good driving stability).